1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing system, an image processing method, a computer readable recording medium storing a program for executing image processing, and the program for executing the image processing, all to be used in an apparatus or a system for executing image correction processing at the time of printing out digital image data obtained with, for example, a digital still camera or the like.
2. Related Background Art
In recent years, for example, digital still cameras have been spread. Consequently, it has become easy to digitize photography images. In particular, images having photographic tones have more frequently treated as digital image data on personal computers. Furthermore, it has become easier to process or edit the digital image data of the images having photographic tones on the personal computers by means of various kinds of application software.
On the other hand, full color hard techniques have also rapidly developed. In particular, in printing techniques using ink jet processes, a technique for decreasing granular feeling owing to ink dots has improved. Consequently, image qualities of printout results have become the same ones of film photos. Furthermore, the printing techniques are relatively simple techniques. Consequently, the printing techniques have been widely spread.
The background art described above urges to develop a technique making it possible to print out digital image data obtained by photography with a digital still camera easily. Furthermore, as for image correction processing at the time of printing out, automatic image correction processing has become necessary more and more for obtaining images always in good conditions after receiving an image correction by means of a piece of application software on a personal computer without operating complicated functions with hands for image correction processing.
Accordingly, various methods have proposed as methods for obtaining good printout results by outputting digital image data after performing image processing such as image correction processing or the like at the time of printing out. One of the methods is, for example, a method for performing image corrections automatically on the basis of the results of analyses of scenes of photography images.
Moreover, for example, methods for the so-called “density correction” have been proposed. The density correction is a kind of image corrections for preventing a photography image from being too bright (too pale) or too dark (too deep) when it is printed out. Furthermore, methods for the so-called “image correction” of a photography image have been proposed also. The so-called image correction is to correct images in which color balance is upset owing to color fogs, unsuitable exposures (in brightness or in contrast), unsuitable color saturation or the like.
Both image processing methods of the “density correction” and the “image correction” adopt a system for automatic image correction. The system analyzes an image to be processed (original image) using a histogram showing a cumulative number of pixels at every luminance value in the original image, and the system corrects the original image on the basis of the result of the analysis.
Moreover, as a function of a digital still camera, it is possible not only to record an image obtained by photography as digital image data in a storage medium such as a memory card or the like, but also to record additional information indicating photography conditions at the time of photography in the storage medium together with the digital image data.
Incidentally, if a scene of an image which is obtained by photography with a digital still camera and is to be an object of image processing (object image) is analyzed by performing the image analysis of the object image to perform the automatic image correction of the object image on the basis of the analysis result in accordance with the conventional image processing method described above, then the automatic image correction to print out images which are considered to be theoretically optimum (standard images) to all of the object images is basically performed.
However, the automatic image correction described above is different from a manual image correction in which a user manually corrects an object image on a personal computer using an application software while ascertaining the object image displayed on the monitor of the personal computer. Since the object image is corrected to be a standard image in the automatic image correction, the corrected image is sometimes different from the intention of the user at the time of obtaining the object image (at the time of photography).
For example, an image obtained under an exposure condition which was intentionally set to be brighter or darker by the user will be output as an image having normal brightness by being corrected to be darker to a brighter image or to be brighter to a darker image. That is, the automatic image correction method corrects any object image to be an image having the same brightness to output it independently of the image quality of the object image.
Moreover, if a user photographs a subject with a digital still camera the white balance of which is intentionally changed with a user's intention of obtaining a specific effect, then the automatic image correction method corrects the photography image to have the optimum color balance similarly.
On the other hand, a digital still camera has a photography mode function to make the photography conditions of the camera be the optimum to a photography scene. If the information of a photography scene, for example, the information concerning which the scene is a scenery or a person, is previously known when an image correction condition is determined correspondingly to the photography mode, then it is considerable that a correction to be a more accurate and preferable image can be realized.
However, since it is impossible to conclude what the photography scene surely is on the basis of the analysis result of an object image obtained by photography, a user has conventionally be obliged to execute the automatic image correction by weakening the correction effect of the correction for preventing the occurrence of harmful influences in a corrected image actually.
Moreover, digital still cameras have improved in their functions in recent years. For example, some of them have such specific effect functions as heighten the color saturation of an image obtained by photography or as change the contrast or the brightness of the image. However, when automatic image correction processing is executed together with the execution of the specific effect functions, the specific effects to be produced by the specific effect functions are sometimes lost owing to the double corrections. In another case, the corrections of the specific effect functions become too strong to make the corrected image be deteriorated.
Accordingly, the inventors of the present invention paid their attention to image data including image information to which a digital still camera added information indicating photography conditions at the time of obtaining the image information by photographing a predetermined scene, i.e. the information indicating various conditions at the time of obtaining the image information. And the inventors proposed a method for performing pertinent image correction processing to the image information by using the image data to analyze the added condition information and then to determine the optimum image correction condition.
However, pieces of condition information added into respective pieces of image data can be considered to have different description formats and different numbers of the items of the condition information correspondingly to the functional improvements of the pieces of condition information. Consequently, a method for judging the description formats and the numbers of the condition items to set a pertinent image correction processing condition is demanded. Moreover, even in the same condition item in a piece of condition information, it is considerable that the meaning of the contents described in the condition item also differs according to the description format or the version of the format. Consequently, a method for setting a pertinent image correction processing condition also in such a case is demanded.